Exhibit 5.1

EXHIBIT 5.1

[DREIER STEIN & KAHAN LLP LETTERHEAD]

February 9, 2007

Board of Directors
Hythiam, Inc.
11150 Santa Monica Boulevard
Suite 1500
Los Angeles, California 90025

Re: Registration Statement on Form S-3

Ladies and Gentlemen:

This opinion is furnished to you in connection with the above-referenced registration statement on Form S-3 (the “Registration Statement”), to be filed with the Securities and Exchange Commission (“SEC”) under the Securities Act of 1933, as amended (the “Act”), for the shelf registration of 215,053 shares of common stock, $0.0001 par value per share (the “Shares”) of Hythiam, Inc., a Delaware corporation (the “Registrant”), on behalf of Selling Stockholder of the Registrant as described in the Registration Statement.

For purposes of this opinion, we have assumed, without independent verification or investigation, that each instrument has been duly and validly authorized, executed, and delivered by each of the parties thereto, the genuineness of all signatures, the authenticity of all documents submitted to us as originals, and conformity with the authentic originals of all documents submitted to us as copies. In rendering the opinions included herein, we have relied upon the factual representations and warranties made by the Registrant and the Selling Stockholders.

Based on and subject to the foregoing, we are of the opinion that the Shares are duly authorized, validly issued, fully paid and nonassessable, and will remain so upon resale in accordance with the Registration Statement.

The opinions contained in this opinion letter merely constitute expressions of our reasoned professional judgment regarding the matters of law addressed herein and neither are intended nor should they be construed as a prediction or guarantee that any court or other public or governmental authority will reach any particular result or conclusion as to the matters of law addressed herein.

This opinion letter is governed by, and shall be interpreted in accordance with, the Legal Opinion Accord (the “Accord”) of the ABA Section of Business Law (1991). As a consequence, it is subject to a number of qualifications, exceptions, definitions, limitations on coverage and other limitations, all as more particularly described in the Accord, and this opinion letter should be read in conjunction therewith.

The opinions expressed herein are written as of and relate solely to the date hereof and are rendered exclusively for your benefit in connection with the Registration. We assume no obligation to advise you of facts, circumstances, events or developments which hereafter may be brought to our attention and which may alter, affect or modify the opinions expressed herein.

We hereby consent to use of this opinion as an exhibit to the Registration Statement and to the use of our name therein and in the related prospectus under the caption “Legal Matters.” In giving such consent, we do not